The present invention relates to a solid-state imaging device in which photoelectric elements, and charge coupled devices (which will be referred to hereinafter as "CCDs") for reading out the optical information of the respective elements integrated on a semiconductor substrate.
A solid-state imaging device requires an imaging plate which possesses a resolution equivalent to that of an imaging electron tube used in television broadcasting at present. This necessitates a matrix of picture elements (photoelectric elements) which are arrayed in a number of about 500 in the vertical direction and in a number of about 800-1000 in the horizontal direction. Scanning elements are also required to correspond to the picture elements. Accordingly, the solid-state imaging device is fabricated by the use of the MOS large-scale integrated circuit technology capable of a high density of integration, and it generally employs CCDs or MOS transistors as its constituents.
FIG. 1 shows the fundamental arrangement of a CCD type solid-state imaging device which features low noise. Numeral 1 designates a photoelectric element which is constructed of, for example, a photodiode. Numerals 2 and 3 designate a vertical CCD shift register and a horizontal shift register, respectively, for delivering photo signals stored in the group of photoelectric elements, to an output end 4. Shown at numerals 5 and 6 are clock pulse generators which produce clock pulses for driving the vertical shift register and the horizontal shift register, respectively. Although clock pulse generators having two phases are illustrated here, either three phase or four phase clock systems may be adopted as well. In addition, numeral 7 indicates a transfer gate by which charges stored in the photodiode are fed into the vertical shift register 2. The present device serves as a black-and-white imaging device in the form illustrated in FIG. 1. When color filters are stacked thereon, it serves as a color imaging device because the respective photodiodes possess color information.
As is well known, in comparison with the electron tube, the solid-state imaging device has a large number of merits owing to its solid state nature, such as small size, light weight, freedom from maintenance and low power dissipation, and it is expected to be a very popular future imaging device. The solid-state device, however, involves the problem that the number of picture elements is still small, so the resolution is relatively low. As described before, the existing device is fabricated with the MOS integrated circuit technology. Nevertheless, the number of picture elements is only about 500 (in the vertical direction).times.400 (in the horizontal direction). Moreover, with regard to interlacing, restrictions in the construction of the vertical shift register make it inevitable to adopt a system wherein odd-numbered rows (arrows 7-1 in solid are read out in the first field, while even-numbered rows (arrows 7-2 in dotted lines) are read out in the second field. Therefore, the solid-state device involves such problems attributed to the interlacing system that 50% of the charges stored in the preceding field remain (afterimage) and that the color resolution is low.